Note: There is a Trophy/Achievement that can be unlocked if you complete the Fourth Survivor.
Here are a few tips that can make your journey as Hunk a little easier.
Zombies: Zombies are unable to attack you whilst they are getting up, use these opportunities to sprint past them.
Combine: As soon as you gain control of Hunk, open up your inventory to combine the High-Grade Gunpowder (Yellow) with the Gunpowder (Large) to retrieve some Shotgun Shells.
Grenades: Don’t waste your Grenades unless you have to, becuase there will be certain points in which Grenades are extremely useful.
Once you’re ready, head onwards and slide down to the Lower Waterway, hug the right side of the room and quickly sprint past all the Zombies as they’re getting up. Once you’ve gotten through the tunnel, head up the stairs to the Control Room, inside you’ll have three Zombies Dogs waiting, sprint past them to the right and drop down to the Monitor Room. You’ll notice a bunch of Zombies eating a corpse, avoid them and head through the door to the Treatment Pool Room.
Note: Use the Shotgun and headshot the Zombies to kill them with one shot.
As soon you enter the Treatment Pool Room you’ll need to take out the Zombie Dogs that are charging towards you, now head across the Bridge and head through the door to southwest of the room. Head downstairs, then left and launch a Hand Grende at the group of Zombies, go across the bridge and follow the path until you reach the Upper Waterway. Getting through the Upper Waterway isn’t going to be so easy as it contains two G-Virus Adults and a few Zombies, stay close to the right wall as you head forward to keep away from the enemies. If you find yourself grabbed, use the Combat Knife to counter.
Once you’ve gotten past the two G-Virus Adults, head up the stairs to the right of the tunnel, avoiding all the Zombies to the Worker’s Break Room, take the lift up to the Underground Faclity.
Note: This would be a good point to use the Mixed Herb (R+B) should you need it.
Exit the lift and head upstairs to the Underground Stairs, inside there will be a few Zombies waiting for you, use another Grenade to take them out and head upstairs and take the first exit into a corridor, where you’ll come across a Licker. Once you’ve gotten past the Licker and entered the Machine Room, follow the room and sprint past all the rising Zombies to the Operators Room.
Tip: It’s a good idea to take the Zombie Dogs out from a distance.
Enter the Operators Room and take out the Zombies with the Shotgun, continue around the room until you see a ladder that you can climb to the Parking Garage.
As soon as you’ve entered the Parking Garage, quickly sprint towards the gate as the Zombies are rising, then use a Flash Grenade to stun the Zombies, giving you a moment to head through the door to the east. You’ll notice a Licker waiting for you at the end of the corridor so take a right and head towards the Kennels to take out the two Zombie Dogs that are hiding before returning to where the Licker is waiting and take it out with three or four shots of the MAG.
Once the Licker has been dealt with, take the left path and follow the corridor around to the Police Station.
Police Station - First Floor
Note: Once you’re near the Watchmen’s Room the Tyrant will appear. You can either stun him with a quick shot to the head with the MAG or dodge past him.
Follow the corridor along and head through the Watchmen’s Room and get past the Tyrant, now enter the corridor and make your way into the Office, take out the Zombies in the room with your Shotgun and make your way to the Main Hall.
Note: Here is a good point to use the Mixed Herb (G+R+B) should you need it.
Unfortunately, you can’t escape just yet because the door is blocked, so make you way into the West Office, and exit the door on the other side to a corridor, head upstairs and through the Shower Room and enter the door to a corridor. You’ll now face two Ivy’s, shoot the orange parts of their body to take them out.
After you’ve gotten past the Ivy, head over to the Lounge and wait for the Zombies to come through the Library door, take them out and go back to the Main Hall, then take out the Zombie Dog and make your way to the Waiting Room. A bunch of Zombies will barge through from the corridor, take them out and head towards the stairs, take out the Licker with a few headshots from the MAG and go upstairs to the Roof.
As soon as you open the door to the Roof, you’ll need to quickly dodge the G-Type Adult and take the ladder down. A Licker and a few Zombies will be waiting at the bottom of the ladder so quickly head through the door and make your way to the Courtyard.
Police Station Courtyard
Although this is the final area of Hunk’s journey, it isn’t going to be easy. Once you’re in the courtyard, throw a grenade in a middle of all the enemies and sprint past them, hugging the right wall in the process. After you’ve gotten past all the enemies run up the stairs and head left to the front entrance of the Police Station.
Complete "The 4th Survivor" extra mode.